Veyance boosts turbocharger hose performance with DuPont™ Vamac® Ultra HT
Ethylene acrylic elastomers (AEM) have come a long way since first introduced to the automotive industry by DuPont in 1975. Following the latest development—DuPont™ Vamac® Ultra—AEM polymers have reached new heights in processing, in resistance to heat, engine and transmission fluids, and to acids from exhaust gas recirculation or blow-by systems in demanding hose, ducting and sealing applications.
By providing real step-change improvements in performance and customer value, Vamac® Ultra has been readily accepted by the industry, as demonstrated in many commercial applications. A notable example is the new TurboBoss™ line of turbocharger hoses by Veyance Technologies, Inc., of Ohio, USA.
In this article, AutoFocus interviews John Sanchirico, Sales and Marketing Specialist at Veyance Technologies, to find out more about Vamac® Ultra in a commercial application, and summarizes the key points of a technical paper entitled "DuPont™ Vamac® Ultra—Latest AEM Polymers and Developments—Meeting Demands of Modern Engine Technology", given by Klaus Kammerer, Technical Consultant, DuPont Deutschland GmbH, at the International Rubber Conference in Nuremberg, Germany on July 2-5, 2012.
Latest in AEM capabilities
Recent changes in engine technology, including the widespread introduction of turbochargers in gasoline engines, exhaust gas recirculation loops, selective catalytic reduction, growing use of bio-fuels, and direct fuel injection at high pressure, have led to new demands and requirements for all underhood components — especially for air ducts, hoses and seals exposed to higher levels of fuel and acid condensates.
Responding to these changes, DuPont has developed additional polymers in the Vamac® Ultra family of higher viscosity AEM grades—including Vamac® Ultra IP and Vamac® Ultra HT—that extend the range of applications beyond the limits of standard AEM. These latest AEM polymers offer excellent resistance to a mix of aggressive fluids used in modern engines.
Major applications for Vamac® Ultra include commercial, industrial and automotive powertrain seals, gaskets, air ducts, turbo charger hose (TCH), transmission oil cooler and PCV hoses, where good dimensional stability, superior physical properties and outstanding heat and fluid aging resistance is required.
High viscosity Vamac® Ultra polymers offer significantly better processing and physical properties than standard Vamac® grades. Depending on grade, capabilities include:
- Faster cure, cleaner molding and better mold flow and release—enabling increased productivity and reduction in total process cost
- Good blow-by and exhaust gas condensate resistance
- Higher heat resistance than standard Vamac® grades
- Enhanced oil resistance, meeting oil swell requirements for polyacrylate (ACM), with better resistance to acids, fuels and water-based fluids
- Excellent long-term heat aging resistance for automotive parts that must provide long-term functionality
- Better property retention after immersion in AdBlue® than standard AEM—beyond the requirements of most specifications for seals in this application
Long-term sealing performance
In compressive stress relaxation tests, Vamac® Ultra grades have not only outperformed standard Vamac® but have increased the gap in long-term sealing performance compared to ACM. While a standard ACM compound obtained from a customer lost more than 50% of its original elongation within the first 1,000 hours at 150°C, Vamac® Ultra IP still had about 100% remaining elongation after 4,900 hours—6 weeks longer than standard AEM.
Vamac® Ultra polymers for turbocharger hoses
AEM has been used with great success in turbocharger hoses since diesel engines were first equipped with turbo systems. Now, the high flexibility of both Vamac® Ultra HT, and the developmental VMX-3121 grade of Vamac® Ultra, mean even better dynamic flexing fatigue resistance for turbocharger hoses. Forthcoming Vamac® Ultra grades will also offer lower swell to oils, diesel or fuel fumes.
Veyance proves Vamac® Ultra
Headquartered in Fairlawn, Ohio, USA, Veyance Technologies, Inc., is the exclusive manufacturer and marketer of Goodyear® Engineered Products worldwide. In addition to turbocharger hose, Veyance manufactures Goodyear®-branded air springs, automotive belts and hoses, power transmission products, conveyor belts and services, industrial and hydraulic hose, rubber track and molded products.
AutoFocus asked John Sanchirico of Veyance Technologies about his company's experiences in specifying standard grades of Vamac® and now Vamac® Ultra HT for the new line of TurboBoss™ 350, 375 and 480 charge air cooler hoses.
Autofocus: Please describe the function of the TurboBoss™ 350, 375 and 480 hoses.
John Sanchirico: The TurboBoss™ line of turbocharger hoses is designed specifically for use in the charge air cooling (CAC) systems of heavy-duty diesel engines, used to cool compressed air exiting the turbocharger and prior to entering the engine. Since the cooler air is more dense than hot air, the engine is able to consume a greater amount of air, and thus operates more efficiently and generates more horsepower.
TurboBoss™ hoses are used to make the flexible connections between the components of the CAC system—i.e., the turbocharger, the charge air cooler, and the engine air intake manifold. TurboBoss™ 350, 375 and 480 constructions are particularly well suited for installation on the "hot side" of the CAC system, before the air has passed through the heat exchanger/charge air cooler.
AutoFocus: Why did you choose Vamac® and Vamac® Ultra HT for these applications?
Sanchirico: Standard grades of Vamac® and Vamac® Ultra HT used in hose constructions have the ideal temperature profiles for the majority of hose applications in CAC systems. In addition, the oil- and chemical-resistance, coupled with the physical properties of constructions based on Vamac®, make them particularly well suited for CAC applications.
AutoFocus: Is Vamac® Ultra HT easy to process?
Sanchirico: Vamac® Ultra HT has a little higher density than some of the other materials we had been working with. Once we gained some experience with the polymer and adjusted our feed rates the material seems to process very well.
AutoFocus: Would you describe this as a particularly demanding operating environment?
Sanchirico: The turbocharger CAC system is a demanding, extreme environment and it is critical to the efficient operation of the engine. The temperatures and pressures throughout the system are considerably higher than those faced by most other formed vehicle hoses. TurboBoss™ hoses are designed specifically for the heavy-duty diesel engine market, which is one of the most severe for turbocharger applications.
AutoFocus: Does it replace an incumbent material, and if so, how is Vamac® superior?
Sanchirico: Vamac® is being used as an economic alternative to silicone in CAC applications. Prior to the use of CAC systems, the air temperatures in turbocharger systems were much higher and silicone was the only suitable material available at the time. Hoses made of Vamac® are especially well suited to the operating temperatures of modern intercooled turbocharger systems, exhibit better sealing properties than silicone, and can be used with less expensive standard type hose clamps. The chemical- and oil-resistance of Vamac® also give it an advantage in use with EGR systems that recirculate some of the engine exhaust gas.
Intercooled turbocharger systems typically have much longer routings than earlier systems where the air was routed directly from the turbocharger to the engine intake manifold. Due to the high cost of silicone, hose assemblies consisting of metal pipes with short sections of silicone hose to make the connections at each end were commonly used. Because hose made of Vamac® is considerably less expensive than silicone hose, single-piece hose assemblies can be used in place of the multi-piece hose and pipe assemblies. Not only does this result in cost savings for the OEM, but it also saves weight—and there are fewer joints in the system, thus reducing the number of potential leak paths.
AutoFocus: Are these hose products expected to last the lifetime of the vehicle?
Sanchirico: The hoses are designed for long-lasting trouble-free service in heavy-duty diesel engine applications. Depending on how the vehicle is operated over time, replacement may be necessary at some point during the lifetime of the vehicle.
AutoFocus: In addition to Vamac®, could you confirm if other DuPont materials—e.g., Viton® fluoroelastomer, Kevlar® aramid fiber and Nomex® fiber—are used in these constructions?
Sanchirico: Viton® is used in the inner tube of the TurboBoss™ 480 construction. All of the constructions are reinforced with DuPont™ Kevlar®, Nomex® or the new hybrid Kevlar®/Nomex® yarn.
AutoFocus: Does Vamac® Ultra HT fully meet your requirements?
AutoFocus: What are the commercial applications and markets for these hoses?
Sanchirico: TurboBoss™ turbocharger hoses are produced in our Delicias, Mexico, plant for installation as standard equipment for heavy-duty turbo-diesel engines used by leading commercial vehicle and industrial equipment OEMs. Currently the primary focus is on the North American market but we are exploring the possibilities of marketing the line in Europe, South America and China.
AutoFocus: Based on your experience with Vamac®, do you plan to extend the Veyance line of products using the DuPont AEM?
Sanchirico: In addition to the CAC system applications, we are finding numerous other transportation hose applications for Vamac® where high temperature and oil resistance is required, such as oil return lines and crank case vent lines.
GOODYEAR® trademarks are used by Veyance Technologies under license from The Goodyear Tire & Rubber Company. For more information, visit http://www.goodyearep.com/
TurboBoss™ is a trademark of Veyance Technologies, Inc.
AdBlue® is a registered trademark of BASF.